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Transcript

  • 1. Introduction Chapter 1
  • 2. The Chapter
    • Networking is a Head Game
      • There is a lot of information to master
      • There are many TLAs (three-letter acronyms)
      • For design and troubleshooting, you must know everything to do anything.
  • 3. Learning Objectives
    • By the end of this chapter, you should be able to
      • Discuss the First Bank of Paradise (FBP), our running case study for this book.
      • Discuss the major types of networked applications.
      • List the eight elements of networks.
      • Explain the major types of networks in businesses: LANs, WANs, internets, intranets, and extranets.
  • 4. Learning Objectives
    • By the end of this chapter, you should be able to
      • Discuss major concerns for network managers: staffing, network architecture, standards, security, wireless networking, efficiency, and quality of service (QoS).
      • Explain the elements and operation of a small home PC network using a LAN.
  • 5. Learning Objectives
    • By the end of this chapter, you should be able to
      • Use some key hands-on network management tools, including bandwidth measurement services, ping, ping 127.0.0.1, tracert, ipconfig, winipconfig, nslookup, and the use of Windows Calculator to compute dotted decimal notation IP addresses .
  • 6. Figure 1-2: Elements of a Network Client Station Mobile Client Station Application Application Server Station Router Mobile Client Station Access Line Trunk Line Switch Switch Switch Switch Trunk Line Outside World Networks connect applications on different stations. Applications are all users care about Message (Frame)
  • 7. Figure 1-2: Elements of a Network, Continued Client Station Mobile Client Station Application Application Server Station Router Mobile Client Station Access Line Trunk Line Switch Switch Switch Switch Trunk Line Outside World Networks connect stations: clients (fixed and mobile) and servers Message (Frame)
  • 8. Figure 1-2: Elements of a Network, Continued Client Station Mobile Client Station Application Application Server Station Router Mobile Client Station Access Line Trunk Line Switch Switch Switch Switch Trunk Line Outside World Message (Frame) Stations (and routers) usually communicate by sending messages called frames The path a frame takes is called its data link
  • 9. Figure 1-2: Elements of a Network, Continued Client Station Mobile Client Station Application Application Server Station Router Mobile Client Station Access Line Trunk Line Switch Switch Switch Switch Trunk Line Outside World Switches move frames to or closer to the destination station Switches handle a packet sequentially Message (Frame)
  • 10. Figure 1-2: Elements of a Network, Continued Client Station Mobile Client Station Application Application Server Station Router Mobile Client Station Access Line Trunk Line Switch Switch Switch Switch Trunk Line Outside World Routers connect networks to the outside world; Treated just like stations Message (Frame)
  • 11. Figure 1-2: Elements of a Network, Continued Client Station Mobile Client Station Application Application Server Station Router Mobile Client Station Access Line Trunk Line Switch Switch Switch Switch Trunk Line Outside World Message (Frame) Access lines connect stations to switches Trunk lines connect switches to switches (and routers) Trunk Line
  • 12. Figure 1-2: Elements of a Network (Recap)
    • Applications (the only element that users care about)
    • Stations
      • Clients
      • Servers
    • Switches
    • Routers
    • Transmission Lines
      • Trunk lines
      • Access Lines
    • Messages (Frames)
    Never talk about an Innovation “reducing cost,” “increasing speed,” etc. without specifying which element is cheaper or faster. For example, multiplexing only reduces the cost of trunk lines; other costs are not decreased
  • 13. Figure 1-3: Multiplexing in a Packet-Switched Network Client Station A Mobile Client Station B Router D Server Station C Trunk line multiplexes the messages of different conversations AC AC AC AC AC AC BD BD BD BD Access Line Trunk Line This reduces trunk line costs through cost sharing by users
  • 14. LANs and WANs
    • LANs transmit data within corporate sites
    • WANs transmit data between corporate sites
    • Each LAN or WAN is a single network
  • 15. Figure 1-4: The First Bank of Paradise’s Wide Area Networks (WANs) Operations Headquarters North Shore OC3 Private Line T3 T3 Bank has multiple facilities connected by multiple WANs
  • 16. Figure 1-5: Local Area Network (LAN) in a Large Building, Continued Router Core Switch Workgroup Switch Workgroup Switch Wall Jack To WAN
  • 17. Internets
    • Most firms have multiple LANs and WANs.
    • They must create internets
      • An internet is a collection of networks connected by routers so that any application on any host on any single network can communicate with any application on any other host on any other network in the internet.
    LAN WAN LAN Application Application Router Router
  • 18. Figure 1-8: Internet with Three Networks Host B Host A Network X Network Y Network Z R1 R2 Route A-B Packet A packet goes all the way across the internet; It’s path is its route
  • 19. Figure 1-8: Internet with Three Networks, Continued
    • Messages in single networks (LANs or WANs) are called frames
    • Message in internets are called packets
      • Travel from the source host to the destination host across the entire internet
    • Within a single network, the packet is encapsulated in (carried in) the network’s frame
    Packet Frame Truck (frame) Package (Packet)
  • 20. Figure 1-8: Internet with Three Networks, Continued Host A Mobile Client Host Server Host Switch Switch X2 Switch X1 Switch Data Link A-R1 Router R1 Frame X Network X Route A-B Details in Network X Packet
  • 21. Figure 1-8: Internet with Three Networks, Continued Router R1 Router R2 Packet Frame Y To Network X To Network Z Network Y Data Link R1-R2 Route A-B Details in Network Y
  • 22. Figure 1-8: Internet with Three Networks, Continued Host B Mobile Client Hosts Switch Z1 Switch Switch Z2 Switch Packet Frame Z Network Z Router R2 Router Data Link R2-B Details in Network Z
  • 23. Figure 1-8: Internet with Three Networks, Continued
    • In this internet with three networks, in a transmission,
      • There is one packet
      • There are three frames (one in each network)
    • If a packet in an internet must pass through N networks,
      • How many packets will be sent?
      • How many frames must carry the packet?
  • 24. Figure 1-11: The Internet Internet Service Provider For User PC Internet Service Provider For Webserver ISP 1 ISP 4 User PC Webserver NAP = Network Access Point Router NAP NAP NAP ISP 2 ISP 3 The Internet Backbone (Multiple Carriers) Access Line Access Line
  • 25. Figure 1-12: The Internet, internets, Intranets, and Extranets
    • internets versus the Internet
    • Intranets
      • Internal internet for use within an organization
      • Based on the TCP/IP standards created for the Internet
    • Extranets
      • Connect multiple firms
        • Only some computers from each firm are on the extranet
      • Use TCP/IP standards
  • 26. Recap
    • Switches versus Routers
      • Switches move frames through single networks (LANs or WANs)
      • Routers move packets through internets
    • Messages
      • Messages in single networks are called frames
      • Messages in internets are called packets
      • Packets are encapsulated within frames
  • 27. Figure 1-13: Major Network Technical Concerns
    • Network Architecture
      • A broad plan for how the firm will connect all of its computers within buildings (local area networks), between sites (wide area networks), and to the Internet
      • New systems must fit the rules of the architecture
      • Undisciplined growth in the past
        • No overall plan
  • 28. Figure 1-13: Major Network Technical Concerns, Continued
    • Network Architecture
      • Legacy networks
        • Use obsolete technologies that do not fit the long-term architecture
        • Many exist in the bank
        • Too expensive to replace quickly; must live with many for awhile
  • 29. Figure 1-13: Major Network Technical Concerns, Continued
    • Network Architecture
      • Scalability
        • The ability of selected technologies to be able to handle growth efficiently
    Cost Per Bit Demand Good Scalability Poor Scalability
  • 30. Figure 1-13: Major Network Technical Concerns, Continued
    • Standards
      • Standards govern message interactions between pairs of entities (Figure 1-14)
        • For example, HTTP request and response messages for WWW access
    Client PC Browser Client Program Webserver Application Server Program Webserver HTTP Request Message HTTP Response Message
  • 31. Figure 1-13: Major Network Technical Concerns, Continued
    • Standards
      • Standards create competition
        • This reduces costs
        • It also stimulates the development of new features
        • Protects the business if the main vendors go out of business
  • 32. Figure 1-13: Major Network Technical Concerns, Continued
    • Standards
      • Competing standards organizations create incompatible standards
      • FBP will standardize to save money
      • LANs: FBP will standardize on Ethernet (some legacy LAN technologies are still in use)
      • WAN standards: will have fewer but still two to four
      • Internetworking: will standardize on TCP/IP
  • 33. Figure 1-13: Major Network Technical Concerns, Continued
    • Security
      • A Major Problem
        • Many attacks
        • Growing trend toward criminal attackers
  • 34. Figure 1-15: Firewalls Log File Legitimate Host Attacker Legitimate Packet Border Firewall Hardened Server Allowed Legitimate Packet Hardened Client PC Internal Corporate Network Border firewall should pass legitimate packets
  • 35. Figure 1-15: Firewalls, Continued Log File Legitimate Host Attacker Attack Packet Border Firewall Denied Attack Packet Network Management Console Hardened Server Hardened Client PC Internal Corporate Network Border firewall should deny (drop) and log attack packets
  • 36. Figure 1-13: Major Network Technical Concerns, Continued
    • Security
      • Virtual Private Networks (VPNs) (Figure 1-16)
        • Provide communication over the Internet with added security
        • Cryptographic protection for confidentiality (eavesdroppers cannot read)
        • Cryptographic authentication (confirms sender’s identity)
  • 37. Figure 1-16: Virtual Private Networks (VPNs) VPN Gateway Internal Server Corporate Site A Corporate Site B VPN Gateway Remote Client PC 2 Site-to-Site VPN Using Gateway Internet Host-to-Host VPN Remote Access VPN Using Gateway Client PC 1 Remote Client PC 3
  • 38. Figure 1-13: Major Network Management Concerns, Continued
    • Wireless Communication
      • To improve mobility
      • Drive-by hackers can eavesdrop on internal communication
      • Drive-by hackers can break into the network bypassing firewalls
    Drive-By Hacker
  • 39. Figure 1-13: Major Network Technical Concerns, Continued
    • Need for Efficiency
      • User demand is growing rapidly
      • Budgets are growing slowly if at all
      • For projects, need burning justification
      • Still add new services by squeezing maximum payback from each dollar
    Money/ Demand Time User Demand Budget
  • 40. Figure 1-13: Major Network Technical Concerns, Continued
    • Quality of Service (QoS)
      • Numerical objectives for performance
      • Transmission speed in bits per second (bps)
          • A bit is a single one or zero
          • NOT bytes per second
      • Increase by factors of 1000, not 1024
        • kilobits per second (kbps)—lower-case k
        • Megabits per second (Mbps)
        • Gigabits per second (Gbps)
        • Terabits per second (Tbps)
  • 41. Figure 1-13: Major Network Technical Concerns, Continued
    • Quality of Service
      • For Transmission Speed, have 1 to 3 places BEFORE the decimal point.
      • Example
          • .5 Mbps is wrong
          • 500 kbps is correct
      • Example
          • 2,300 Mbps is wrong
          • 2.3 Gbps is correct
      • Example
          • 473.2 Mbps is correct
    New Not in the Book
  • 42. Figure 1-13: Major Network Technical Concerns, Continued
    • Quality of Service
      • Typical transmission speeds in most firms:
        • LANs: 100 Mbps to each desktop
        • WANs: most site-to-site links only are 56 kbps to a few megabits per second because long-distance transmission is very expensive and so must be used more sparingly
  • 43. Figure 1-13: Major Network Technical Concerns, Continued
    • Quality of Service
      • Congestion, Throughput, Latency, and Response Time
        • Congestion: when there is too much traffic for the network’s capacity
        • Throughput: The speed users actually see (often much less than rated speed)
        • Individual throughput is less than total throughput on shared-speed links
  • 44. Figure 1-13: Major Network Technical Concerns, Continued
    • Quality of Service
      • Congestion, Throughput, Latency, and Response Time
        • Latency: delay (usually measured in milliseconds or ms)
        • Within corporations, latency is typically under 60 ms 90% of the time
        • On the Internet, typically 30 ms to 150 ms
  • 45. Figure 1-13: Major Network Technical Concerns, Continued
    • Quality of Service
      • Congestion, Throughput, Latency, and Response Time
        • Response Time
          • The time to get a response after a user issues a command
          • A quarter second or less is good
  • 46. Figure 1-13: Major Network Technical Concerns, Continued
    • Availability
      • Availability is the percentage of time a network can be used
      • Downtime: when the user cannot use the network
      • Want 24x7 availability
      • Telephone network gives 99.999% availability
      • Typical networks reach 98% today
  • 47. Figure 1-13: Major Network Technical Concerns, Continued
    • Error Rate
      • Measured as the percentage of messages damaged or lost
      • Substantial error rates can disrupt applications
      • Substantial error rates generate more network traffic because of retransmissions
  • 48. Figure 1-19: Network Interface Cards (NICs) (Photo) Internal NIC. Installed inside systems unit. Plugged into expansion slot on the mother board. PC Card NIC. Installed in PC Card slot in notebook and some PDAs.
  • 49. Figure 1-23: Logical Functions of the Access Router DHCP Server Function Router Function NAT Function Switch Function Access Router Cable Modem
  • 50. Figure 1-24: Ethernet Switch Operation Switching Table Port Host 10 A1-44-D5-1F-AA-4C 13 B2-CD-13-5B-E4-65 15 C3-2D-55-3B-A9-4F 16 D4-47-55-C4-B6-9F UTP UTP UTP UTP Ethernet Switch A1-44-D5-1F-AA-4C B2-CD-13-5B-E4-65 D4-47-55-C4-B6-9F C3-2D-55-3B-A9-4F Frame To C3… Frame To C3…
  • 51. Figure 1-25: Frames and Packets Internal Router Packet in DOCIS Frame Access Router Cable Modem Packet in Ethernet Frame A1-BD-33-6E-C7-BB IP address = 192.168.0.3 PC in Emily’s Room B2-CD-13-5B-E4-65 IP address = 192.168.0.2 PC in Study Packet is always carried (encapsulated) in a frame
  • 52. Figure 1-26: Dynamic Host Configuration Protocol (DHCP) Access Router Cable Modem A1-BD-33-6E-C7-BB PC in Emily’s Room B2-CD-13-5B-E4-65 PC in Study ISP DHCP Server 1. IP Address = 60.47.112.6 A DHCP Server provides User PCs with a temporary IP Address each time the user connects to the Internet The ISP only Gives each home a Single IP address
  • 53. Figure 1-26: Dynamic Host Configuration Protocol (DHCP), Continued Internal DHCP Server Access Router Cable Modem A1-BD-33-6E-C7-BB IP address = 192.168.0.3 PC in Emily’s Room B2-CD-13-5B-E4-65 IP address = 192.168.0.2 PC in Study ISP DHCP Server 1. IP Address = 60.47.112.6 2. IP Address = 192.168.0.2 2. IP Address = 192.168.0.3 The access router’s Internal DHCP server Gives private IP Addresses to each PC
  • 54. Figure 1-27: Network Address Translation (NAT) Access Router Cable Modem Webserver IP address= 123.7.86.285 1. Packet from 192.168.0.2 Internal NAT Module PC in Study 192.168.0.2 2. Packet from 60.47.112.6 The access router’s NAT module translates between the private IP addresses and the single ISP-given IP address
  • 55. Figure 1-27: Network Address Translation (NAT), Continued Access Router Cable Modem Webserver IP address= 123.7.86.285 4. Packet to 192.168.0.2 Internal NAT Module PC in Study 192.168.0.2 3. Packet to 60.47.112.6
  • 56. Figure 1-28: The Domain Name System (DNS), Continued Host Name IP Address … … … … Voyager.cba.hawaii.edu 128.171.17.13 … … DNS Table DNS Host Originating Host’s DNS Resolver DNS Request Message “ The host name is Voyager.cba.hawaii.edu” DNS Response Message “ The IP address is 128.171.17.13”
  • 57. Figure 1-29: Converting Binary IP Addresses to Dotted Decimal Notation 127.171.17.13 Dotted Decimal Notation 13 17 171 127 Convert Segments to Decimal 00001101 00010001 10101011 01111111 8-Bit Segments 01111111101010110001000100001101 Binary IP Address
  • 58. Topics Covered
    • The First Bank of Paradise
    • Networked Applications
    • Packet switching and Multiplexing
    • LANs versus WANs
      • Within a site versus between sites